Duke

Duke is the eleventh rank of the Imperial aristocracy, and is generally seen as "having made it" in the hierarchy of the Empire. A Duke controls a region so vast that it is easily equivalent to smaller-sized nations outside the Empire. Typically, a Duke wields considerable political influence as well, and it is the first rank where one can request an Exterminatus from Imperial High Command.

Responsibilities
A Duke is expected to see things in a grander scope than any previous rank of Noble. They travel throughout the Empire, often following the Emperor and his Council, in order to take in the full breadth of what occurs. A Duchy, as their demense is known, consists easily of two to three thousand systems across several Marches, many of these systems having three or more populated worlds.

Furthermore, a Duke controls a military force in excess of most races outside humanity. With the exception of a handful of advanced species, among them the Council races, a Duke of the Terran Empire commands a terrible mass of troops and warships. Ducal Flagships are usually seen at the forefront of any Imperial Crusade, and are some of the most singularly terrifying objects in the known galaxy.

Historically, the word of a Duke is considered sacrosanct, and often they have the power to end the career of any upstart Noble of lesser rank. For this reason, they are both admired and feared by their lessers. A Duke who has served for a long period and has led Imperial forces in numerous battles may be lucky enough to be promoted to a Grand Duke.

Exterminatus
The feared Exterminatus is an order issued by Imperial High Command, at the request of a Duke or greater Noble, to completely annihilate an entire system. This is done by "glassing" the surface of worlds with massive blasts from specially-equipped siege vessels or dreadnoughts. Occasionally, this process is undertaken by a Titan-class vessel, which is capable of not only sterilizing the surface of multicellular life, but often will cripple the planet to the point of never producing living organisms again.

An Exterminatus is not to be taken lightly, and this is why only a Duke or higher can even request one. They are no guarantee, and in many cases the request is denied, but the simple fact that one might be called is usually enough to keep the enemies of a Duke at bay. Seventeen Exterminati have been used since the founding of the Empire, and in every case, there were no survivors.